Method and apparatus for reclaiming a metal from a CMP process for use in an electroplating process

ABSTRACT

A method and apparatus is disclosed for reclaiming a metal from the effluent of a chemical mechanical planarization (CMP) process and using the reclaimed metal in an electroplating process. The steps of the method include using a chemical solution in a CMP process to remove material from a semiconductor device. An effluent is produced by this step that contains a dissolved first species removed from the semiconductor device. Then a second step of treating the effluent is performed to remove the dissolved first species and to produce a reclaimed metal. Then a third step of using the metal in an electroplating process is performed.

This application is a continuation-in-part application of Ser. No.09/484,933 filed Jan. 18, 2000.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to chemical mechanicalplanarization (CMP) and electroplating of a metal film on semiconductordevices, and more particularly, to a method and apparatus for reclaiminga metal from the effluent of a CMP process and using said reclaimedmetal in an electroplating process.

2. Description of Related Art

Electroplating or electrodeposition, is a well-known process used todeposit metals such as copper from a chemical solution onto an electrodecalled a cathode and is described in the following articles, that arehereby incorporated by reference:

1. Loweheim, F. A., ed., Modem Electroplating, 3^(rd) edition,Electrochemical Society, 1974.

2. Paunovic, M. and Schlesinger, M., Fundamentals of Electrodeposition,Electrochemical Society Series, John Wiley and Sons, 1998.

Electroplating has recently received a tremendous amount of attention asa process for depositing a metal such as copper onto the surface of asemiconductor device. Prior art FIG. 1 is a schematic representation ofthe typical components of an electroplating system. In thisrepresentation, an electroplating chemical solution 205 is fed from alarger storage chamber (not shown) into an electroplating chamber 210.The electroplating chamber 210 contains an anode 215 and a cathode 220,both of which are immersed in the chemical solution 205. The anode 215and cathode 220 may be constructed of copper, platinum, carbon, steel,or other conductive materials typically used for electrodeposition.Electricity is generated from a power source 225 and is passed betweenthe anode 215 and cathode 220 such that electrons flow from the anode215, through the wire 230, to the cathode 220. The power source 225 maybe a battery, a potentiostat or other potential creating device that iswell known in the industry.

As is well known in electrodeposition, this will cause a reductionreaction to occur at the cathode 220 and an oxidation reaction to occurat the anode 215. In electroplating, the reduction reaction is achemical reaction where a species which is on the surface of theelectrode, or is dissolved in the chemical solution 205, such as apositively charged metal ion (M⁺), gets reduced, i.e. charged by atleast one electron as represented by the following reaction:

M⁺+e⁻→M

This causes the metal (M) to become “plated” onto the cathode so that ametal film is grown onto the surface of the cathode 220. The metal maybe any conductive material such as copper, tungsten, aluminum, iron,nickel, titanium, tantalum, palladium, iridium, platinum, silver, ormetal alloys. In the semiconductor industry, a semiconductor wafercontaining semiconductor devices is typically used as the cathode 220causing a film of metal to become plated onto the semiconductor deviceson the wafer.

An oxidation reaction is a chemical reaction where a species at theanode 215 gives up at least one electron. The species in an oxidationreaction might be a species in the chemical solution 205 such asnegatively charged ions (An⁻) which become oxidized as represented bythe following reaction:

An⁻→An+e⁻,

The species in an oxidation reaction might also be the metal material ofthe anode 215. In this case, during processing the metal loses at leastone electron and becomes dissolved in the chemical solution 205 as isrepresented by the following reaction:

M→M⁺+e⁻

CMP is a well-known process used to remove and planarize materials on asemiconductor device such as copper, tungsten, aluminum, silicon,silicon dioxide, or silicon nitride. As part of the semiconductor devicefabrication process, these types of materials are normally deposited onthe surface of a semiconductor device by typical methods such aselectroplating or chemical vapor deposition and then removed andplanarized using a CMP process. Prior art FIG. 2 is a perspective viewof a CMP system used to perform a conventional CMP process with anexploded cross-sectional view 9 of a semiconductor device beingplanarized. In FIG. 2, the CMP system 5 includes a polishing pad 10,placed on a rotating table 12. The semiconductor wafer 14 containing thesemiconductor device is held in a rotating carrier 16, and the frontsurface 17 of the semiconductor device on the wafer 14 is rubbed againstthe polishing pad 10 to planarize the semiconductor device.

During a conventional CMP process, a chemical liquid 18 is also requiredand is delivered to the CMP system 5 by a first delivery device 7.Although not shown, typically a fine particle abrasive such as aluminaor silica, normally already mixed into the chemical liquid 18 and knownconventionally as a slurry, is also required for the CMP process. Thediameter of the abrasive particles typically ranges from ten nanometersto ten microns. The abrasive particles need not be already mixed in thechemical liquid 18, but rather may be embedded in the polishing pad 10.Alternatively, the abrasive particles may also be separately deliveredto the CMP system 5 by a second delivery device (not shown) and mixedwith the chemical liquid 18 on the polishing pad 10. In operation, thechemical liquid 18 and/or slurry is used to continuously wet thepolishing pad 10 while the pad 10 is mechanically rubbed against thefront surface 17 of the semiconductor device enabling removal andplanarization of the deposited material on the wafer 14.

Recently, CMP and electroplating have received a tremendous and growingamount of investigation and engineering as enabling technologies formanufacturing high-speed semiconductor devices. This is becausehigh-conductivity copper is now being used as the interconnect material(replacing aluminum) to connect multiple semiconductor devices on asemiconductor device. Electroplating has been used to deposit copper onsemiconductor wafers. With the use of copper, more and more layers areformed on a single semiconductor device and in a more compact area. Withthe additional layers, the CMP and the electroplating processes are bothused more frequently since each such layer requires metal deposition andplanarization prior to adding subsequent layers. Thus, theelectroplating and CMP processes are becoming increasingly morenecessary as more layers are formed and increasingly more important tothe overall semiconductor manufacturing process.

Two areas of concern in both the CMP and electroplating processes arethe high cost of consumables used and the environmental impact ofdiscarding used CMP and electroplating chemical liquids. Inelectroplating, the high cost of consumables generally stems from itemsthat are “consumed” during processing such as the electroplatingchemical solution or the anode material that becomes dissolved duringprocessing as described in FIG. 1. In CMP, the high cost of consumablesgenerally stems from items such as the chemical liquid or slurry andpolishing pads of FIG. 2, to name a few. For example, a copper CMPprocess may require about 600 cubic centimeters of chemical liquid foreach semiconductor wafer processed. At this rate, a semiconductormanufacturing facility that produces 5,000 completed semiconductorwafers each week, and that requires six copper CMP processes for eachcompleted semiconductor wafer, may require about one million liters ofchemical liquid each year for the copper CMP process. At current slurrycosts of about $10.00 per liter, this translates to a cost of over tenmillion dollars annually.

As mentioned above, disposal of the used CMP chemical liquids or the CMPeffluent is another concern in CMP processing. Prior art FIG. 3 is atypical disposal system for CMP effluent in a semiconductormanufacturing facility. In Prior Art FIG. 3, a chemical liquid or slurry20 contained in storage tank 25 is sent to the CMP system 30, such asthe CMP system 5 of prior art FIG. 2. The “used” slurry or chemicalliquid from the CMP process flows through a drain 31 and is sent to afacility 35 for adherence to environmental regulations.

For a copper CMP process, the facility 35 might remove dissolved copperin order to meet Environmental Protection Agency (EPA) requirements formaximum permitted contamination or effluent levels. For example, theseEPA requirements for maximum permitted effluent levels may be 0.6 partsper million. In a copper CMP process on semiconductor wafers of 200millimeters in diameter, with a film of deposited copper that is onemicrometer in thickness, the concentration of copper in the effluentproduced during copper CMP processing would be about 500 parts permillion. This effluent would likely require costly procedures to removethe copper contained in the effluent.

To relieve these concerns, several solutions have been suggested. Forexample, in U.S. Pat. Nos. 5,664,990 titled “Slurry Recycling in CMPApparatus,” and 5,755,614 titled “Rinse Water Recycling in CMPApparatus,” a solution of capturing a used slurry (in one patent) andrinse water (in the other patent) after the CMP process to continuouslyblend the used slurry or rinse water with fresh slurry is disclosed.However, there is no disclosure in these patents for removing dissolvedmaterials, such as dissolved copper, from the slurry or rinse water.Only a filtration system is disclosed that removes particles that havenot been dissolved in the slurry or rinse water. Thus, the recycledslurry still contains much of the dissolved material that was removedfrom the semiconductor wafer during the CMP process, which, in turn,degrades the quality of the recycled slurry. Additionally, there is nomention in this patent of reclaiming a metal from the CMP effluent foruse in an electroplating process.

U.S. Pat. No. 5,791,970 titled “Slurry Recycling System forChemical-Mechanical Polishing Apparatus” also discloses a manner ofrecycling CMP slurry using an endpoint-monitoring system. Theendpoint-monitoring system monitors the impact of the slurry on theremoval rate of the CMP process and accordingly controls the rate ofrecycled slurry usage, thereby reducing any negative impact the recycledslurry may have on the CMP process. This solution, however, much likethe prior patents discussed above, does not provide for removing thedissolved material found in the effluent that is removed from thesurface of the semiconductor wafer. Again, the recycled slurry containscontaminated, dissolved materials that degrade the quality of therecycled slurry and affects the performance of the CMP process usingthat recycled slurry. Also, there is no mention in this patent ofreclaiming a metal from the CMP effluent for use in an electroplatingprocess.

A need therefore exists for a method in electroplating and in CMP thatalleviates the high costs of consumables used and that reduces waste insuch process. Any solution to this need must be capable of doing morethan merely filtering particles in the slurry. The solution must becapable of removing dissolved materials from a used slurry or chemicalliquid, and reusing the reclaimed chemical solution or reclaimed metalwithout having a detrimental impact on the performance of the CMP and/orelectroplating processes.

SUMMARY OF THE INVENTION

The present invention provides for a method of reclaiming a metal fromthe effluent of a CMP process and using said reclaimed metal in anelectroplating process. The invention also provides a method ofrejuvenating a chemical solution used in a first CMP process for reusein a second CMP process. This method is performed in three steps. Afirst step uses the chemical solution in a first CMP process to remove ametal material from a semiconductor device undergoing the first CMPprocess. This step produces an effluent that contains a dissolved firstspecies removed from the semiconductor device during the first CMPprocess. The second step involves treating the effluent with a firstelectroplating process to remove the dissolved first species. Thissecond step may produce a rejuvenated chemical solution that may then beused in a second CMP process. The second step causes the dissolved firstspecies to be electroplated as a reclaimed metal. The third step usesthe reclaimed metal in a second electroplating process.

The dissolved first species may include, for example, ions of copper,tungsten, aluminum, iron, nickel, titanium, tantalum, palladium,iridium, platinum, silver and the like.

In one embodiment of the present invention, as part of the treating stepof the method of the present invention, the step of adding a secondspecies, such as an oxidizer, to the rejuvenated chemical solution isincluded. This adding step, in this embodiment, may be performed before,after, or simultaneous to, the treating step of the method of thepresent invention.

In another embodiment of the treating step of the method of the presentinvention, ion exchanging is performed to remove the dissolved firstspecies from the effluent.

In a further embodiment of the present invention, the treating step ofthe method of the present invention may be performed by precipitatingthe dissolved first species. In yet another embodiment, an additionalfiltering step is performed to remove particles from the effluent, whichmay also be removed using a centrifuging method.

The apparatus of the present invention includes, in one embodiment, aCMP means for removing material from a semiconductor device producing aneffluent containing a dissolved first species, a first electroplatingmeans for treating the effluent to remove the dissolved first speciesand produce a reclaimed metal, and a second electroplating means inwhich the reclaimed metal is used. The CMP means, in one embodiment,includes a polishing pad, a rotating table, a wafer containing asemiconductor device and a rotating carrier to hold the wafer. The CMPmeans further includes delivery devices to deliver a chemical solutionto the wafer and a waste device to remove used chemical solutions from aCMP process. The first and second electroplating means, in oneembodiment, each include an electroplating chemical solution, a chemicalsolution storage chamber, an electroplating chamber, an anode, acathode, and a power source such as a battery or a potentiostat. In oneembodiment, the cathode of the first electroplating means is used as theanode of the second electroplating means.

In another embodiment, the CMP means and the second electroplating meansare separate chambers integrated together into a larger device.

It is noted that the CMP and electroplating means are not limited to thecomponents described in this embodiment, but includes all well-knowncomponents used to CMP or electroplate materials. For example, insteadof a rotating table and/or a rotating carrier, said CMP means mayinclude any mechanism that can cause the relative motion of the waferagainst the polishing pad. As another example, the CMP and/orelectroplating means may include components for cleaning and/or dryingthe surfaces of the materials either during or after processing. Suchcomponents may include, brush scrubbers, megasonic devices, and/orspin-rinse dryers.

In several embodiments an ion exchange device, a filtering device,and/or a centrifuging device are used to treat the effluent from the CMPprocess. The ion exchange device performs the well-known procedure wherea material (e.g. resin) in a system removes a first ion while a secondion is introduced to the system to thereby “exchange” the ions. Thefiltering device and the centrifuging device each perform the well-knownprocedure of removing a solid particle from the CMP effluent. In oneembodiment, the ion exchange device and the filtering device are used inaddition to the electroplating device to produce a rejuvenated chemicalsolution and a reclaimed metal.

BRIEF DESCRIPTION OF THE DRAWINGS

A better understanding of the present invention can be obtained when thefollowing detailed description of a preferred embodiment is consideredin conjunction with the following drawings, in which:

Prior art FIG. 1 is a perspective view of an electroplating system todeposit metal material on a surface.

Prior art FIG. 2 is a perspective view of a CMP system used to perform aconventional CMP process with an exploded cross-sectional view of asemiconductor device being planarized;

Prior art FIG. 3 is a schematic representation of a conventional CMPdisposal system;

FIG. 4 is a cross-sectional view of an embodiment of a semiconductordevice to be planarized using an embodiment of the method of the presentinvention and the apparatus of the present invention;

FIG. 5 is a cross-sectional view of an embodiment of a semiconductordevice after being planarized using an embodiment of the method of thepresent invention and the apparatus of the present invention;

FIG. 6 is a schematic view of an embodiment of the CMP apparatus of thepresent invention.

FIG. 7 is a schematic view of an embodiment of the apparatus of thefirst electroplating device of the present invention; and

FIG. 8 is a flow chart of an embodiment of the method of the presentinvention.

It will be appreciated that for simplicity and clarity of illustration,elements illustrated in the drawings have not necessarily been drawn toscale. For example, the dimensions of some of the elements areexaggerated relative to other elements for purposes of clarity. Further,where considered appropriate, reference numerals have been repeatedamong the drawings to represent corresponding or analogous element.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

FIG. 4 is a cross-sectional view of a semiconductor device that will beplanarized using an embodiment of the method of the present invention.In FIG. 4, the semiconductor device is formed from a substrate 40 thatmay be made of any conventional semiconductor material such asmonocrystalline silicon, germanium, silicon on insulator or other typesof semiconductor wafer material. A source region 45 and a drain region50 have been formed in the substrate 40 using conventional semiconductordepositing techniques after formation of the gate oxide 55 and gate 60.As is well known in the industry, gate oxides 55 are typically formed ofinsulating type of material such as silicon dioxide while the gate 60 isa conducting material such as tungsten or polysilicon. The drain 50 andsource 45 regions likewise are made of conventional semiconductormaterial that is doped of n-type or p-type conductivity. Followingformation of the gate 60, a first interlevel dielectric (ILD) layer 65is formed. The ILD layer 65 may be made of any conventional dielectricmaterial such as silicon dioxide or materials with low dielectricconstant such as organic polymers. The ILD layer 65 is etched, as iswell known in the art, to form an opening that is filled with a firstconductive material 70 such as silicon, copper, tungsten, aluminum,iron, nickel, titanium, tantalum, palladium, iridium, platinum orsilver, to form a contact plug 75. Although it is not shown, the contactplug 75 may also be lined with a diffusion barrier material such astungsten nitride, titanium nitride or tantalum nitride between the firstILD material 65 and the first conductive material 70. The contact plug75 provides ohmic contact to the source region 45. Although it is notshown in the cross sectional plane of FIG. 4, a similar contact plug, ascontact plug 75, is formed for the drain region 50.

Still in FIG. 4, a second ILD layer 80 is formed and etched, usingconventional techniques known to those skilled in the art, to formtrench 85. The trench 85 is then filled with a second conductivematerial 90 such as copper, tungsten, aluminum, iron, nickel, titanium,tantalum, palladium, iridium, platinum or silver. In one embodiment ofthe method of the present invention, the trench is filled with copperusing the second electroplating process. The cross sectional plane inFIG. 4 shows the second conductive material 90 in ohmic contact with thecontact plug 75. Although it is not shown, there may also be a diffusionbarrier material such as tungsten nitride, titanium nitride or tantalumnitride between the second ILD material 80 and the second conductivematerial 90. The thickness of the second conductive material 90 istypically on the order of 300 nanometers to 1500 nanometers. It is notedthat the dimensions and methods of depositing the layers shown in FIG. 4are well known to those skilled in the art.

It is understood that the manner of making the semiconductor device ofFIG. 4 is well known in the art and therefore the description aboverelating to FIG. 4 is sufficient to enable one of ordinary skill in theart to form such device to be planarized using the method and apparatusof the present invention. It is further noted that the material removedand planarized by the CMP method and apparatus of the present inventionmay be any of the materials typically used in semiconductor devicefabrication such as silicon, silicon dioxide, silicon nitride, titanium,titanium nitride, tantalum, tantalum nitride, tungsten, tungstennitride, iron, nickel, palladium, iridium, platinum, silver, aluminum orcopper.

FIG. 5 is a cross-sectional view of the semiconductor device of FIG. 4after such device has been planarized using an embodiment of the methodand apparatus of the present invention. In FIG. 5, the second conductivematerial 90 of FIG. 4 has been planarized and removed to form aninterconnect line 100. The CMP process planarizes and removes the secondconductive material 90 such that the second conductive material 90remains in the trench 95 and is coplanar with the second ILD layer 80.

FIG. 6 is an embodiment of the CMP apparatus of the present invention.In FIG. 6, a CMP means 120 for removing materials from a semiconductordevice is shown. The CMP means 120 includes the items of prior art FIG.2 (not shown), including a semiconductor wafer having semiconductordevices thereon, a rotating table to place the wafer on, a polishing padand a rotating table. The semiconductor wafer (not shown) containing thesemiconductor device is held in a rotating carrier (not shown), and thefront surface of the semiconductor device on the wafer is rubbed againstthe polishing pad (not shown) to remove and planarize the semiconductordevice. It is noted that the CMP means further includes a chemicalsolution (not shown) contained in storage tank 125 that is used toremove material from the semiconductor device being planarized.

The chemical solution contained in storage tank 125 and delivered to theCMP means 120 by the delivery device 126 is either a conventional slurrycontaining fine particle abrasive particles such as alumina or silica,or a chemical solution not containing fine particle abrasive particles.Typical chemical solutions may contain one or more of the following:acids, bases, oxidizing agents, surfactants, complexing agents, or otherorganic and inorganic chemical species.

In one embodiment, the CMP means 120 performs a portion of the CMPprocess. The CMP process involves a number of separate CMP processes.That is, in this embodiment, a first CMP process may be followed by asecond CMP process and so on. Each CMP process involves transferring thechemical solution that is drawn from the storage tank 125 and/or drawnfrom the treating means 140 to the CMP means 120. In the case where thesecond conductive material 90 in FIG. 4 is copper, the starting chemicalsolution may contain one or more oxidizing agents (Ox) such as hydrogenperoxide, ammonium periodate, ferric nitrate or any other oxidizingagent. The oxidizing agent can react with the copper causing the copperto become oxidized and the oxidizing agent to become reduced asrepresented by the following chemical reaction:

Cu (s)+20x→Cu²⁺+20x⁻

Cu (s) is the symbol for solid metal copper and Ox represents theoxidizing agent. The oxidized copper species, Cu²⁺, and the reducedoxidizing agent species, Ox⁻, will typically be dissolved in a wastesolution (not shown) that is transferred, in this embodiment, to afiltering means 135 by the drain 130. Additionally, the chemicalsolution may also contain complexing agents that can bind to theoxidized copper, Cu²⁺, during the CMP process and form a copper complexthat is typically dissolved in the waste solution.

In the embodiment shown in FIG. 6, the first CMP process begins at thestorage tank 125 by sending chemical solution or slurry to the CMP means120. The storage tank 125 typically contains “fresh” or unused chemicalsolution or slurry. After the CMP means 120 performs the CMP on thesemiconductor device, the used chemical solution or slurry, termed“effluent,” is drained through the drain 130 to the filtering means 135.The effluent contains numerous dissolved species, including a dissolvedfirst species such as copper. The filtering means 135 involves afiltering step in which a solid or undissolved particle is removed fromthe effluent. The filtering step may involve flowing the effluentthrough a filter or membrane enabling the solid particle to be trappedin the filter or membrane.

In a further embodiment, the filtering means 135 may also involve acentrifuge step in which the solid particle is removed by centrifugalforce generated by rotation. The centrifuge step may be instead of, orin addition to, the filtering step. Having removed solid particle orparticles, the effluent containing dissolved first species then flowsout of the filtering means 135 and is transferred to the treating means140. The treating means 140 takes the effluent from the filtering means135 and treats the effluent by electroplating to remove the dissolvedfirst species to produce a reclaimed metal. In this embodiment, arejuvenated chemical solution is also produced. The rejuvenated chemicalsolution is sent out of the treating means 140 through the treatingdrain 150. In this embodiment, the rejuvenated chemical solution ismixed with unused chemical solution or slurry, sent from storage tank125, at position X. At position X, a second CMP process begins by mixingthe rejuvenated chemical solution from the treating means 140 with thefresh slurry and sending both of these items to the CMP means 120.

It is noted that the first CMP process may use either unused chemicalsolution from storage tank 125, or rejuvenated chemical solution fromthe treating means 140, or a mix of chemical solutions from both thestorage tank 125 and the treating means 140. It is also noted that thechemical solution exiting the treating means 140 contains less dissolvedfirst species than the effluent exiting the CMP means 120 through thedrain 130.

The treating means 140 is any apparatus that performs electrodepositionor electroplating as is well-known in the art, that is, anelectroplating device. Electrodeposition, or electroplating, is awell-known process for plating a metal such as copper onto an electrode.In an embodiment of the method of the present invention, a firstelectroplating process in a first electroplating device treats theeffluent from a copper CMP process. The copper is plated onto anelectrode and is reclaimed, and the electrode with the reclaimed copperis used as an electrode in a second electroplating device.

In one embodiment, the CMP means and the second electroplating means areseparate chambers integrated together into a larger device.

In a further embodiment, a monitoring means may be added to the CMPapparatus of the present invention to monitor the concentration of thedissolved first species in the effluent. For example, the monitoringmeans may be optical or electrochemical based technologies, atomicabsorption, or any means that is able to detect the extent to which thedissolved first species has been removed. It is noted that themonitoring means may be present in the CMP apparatus in variouslocations throughout the apparatus, including at the drain 130 of FIG. 6to monitor how much dissolved first species is in the effluent afterleaving the CMP means of FIG. 6. Said monitoring means may also bepresent within the treating means 140 in FIG. 6.

In another embodiment of the method of the present invention, ionexchanging is performed to remove the dissolved first species from theeffluent. This ion-exchange step may be performed before, after, orduring the first electroplating process. Ion exchanging performs thewell-known procedure where a material (e.g. resin) in a system removes afirst ion while a second ion is introduced to the system to thereby“exchange” the ions.

FIG. 7 is a schematic view of an embodiment of the treating means shownin FIG. 6. In FIG. 7, the effluent 170 is contained in a chamber 175 andthe anode 180 and the cathode 185 are immersed in the effluent 170. Theanode 180 and cathode 185 may be constructed of copper, platinum,carbon, steel, aluminum or other conductive materials typically used forelectrodeposition. Electricity is generated from a power source 195 andis passed between the anode 180 and cathode 185 such that electrons flowfrom the anode 180, through the wire 190, to the cathode 185. The powersource 195 may be a battery, a potentiostat or other potential creatingdevice that is well known in the industry. As is well known inelectrodeposition, this will cause a reduction reaction to occur at thecathode 185. A reduction reaction is a chemical reaction where a speciesin a liquid gets reduced, i.e. charged by at least one electron. In oneembodiment, copper ions, Cu²⁺, that were generated during the first CMPprocess as described previously, migrate through the effluent andundergo the following reduction reaction at the cathode 185:

Cu²⁺+2e⁻→+Cu (s)

Where e⁻ represents electrons generated at the cathode 185. This willreclaim solid metal copper as a copper film becomes plated onto thecathode 185. In one embodiment, the cathode 185 shown in FIG. 7 is usedin the first electroplating process to reclaim the copper. After thisreclaiming step, the cathode 185, on which the reclaimed copper isdeposited, is removed and used as the anode in a second electroplatingprocess.

As is also well known in electrodeposition, an oxidation reaction willoccur at the anode 180. In one embodiment, the reduced oxidizing agentspecies, Ox⁻, migrate through solution and undergo the followingreduction reaction at the cathode 185:

Ox⁻→Ox+e⁻

Electricity will continue to flow until the concentration of copper hasbeen reduced to a predetermined acceptable level. The copperconcentration of the effluent from a copper CMP process may range from 1to 1000 parts per million and may be reduced by greater than 99% by theelectrodeposition process.

FIG. 8 is a flow chart of an embodiment of the method of the presentinvention. In FIG. 8, a first step 250 uses the chemical solution in theCMP means 120 of FIG. 6 for the first CMP process to produce theeffluent going into the drain 130 of FIG. 6. In this embodiment, thefirst step 250 removes material from the semiconductor device as shownin FIGS. 3 and 4. The effluent produced from this step contains thedissolved first species, such as one or more ions of copper, tungsten,aluminum, iron, nickel, titanium, tantalum, palladium, iridium,platinum, silver, and the like. The second step is the treating step 255where the effluent is treated to remove dissolved first species aslisted above. This treating step may produce a rejuvenated chemicalsolution for reuse in the second CMP process described with regard toFIG. 6. This treating step is accomplished by a first electroplatingprocess to remove the dissolved first species from the effluent andproduce a reclaimed metal on the cathode 185 as shown in FIG. 7. In thethird step the reclaimed metal from the treating step is used in asecond electroplating process.

The treating step further includes, in another embodiment, a step ofadding a second species to the rejuvenated chemical solution. Thisadding step may be performed before or after the effluent is treated,with, for example, the electroplating device of FIG. 7, or simultaneousto that treatment. In this embodiment, the second species is a componentof the chemical solution that was reacted during the first CMP processsuch as an oxidizing agent. Typical oxidizing agents include, hydrogenperoxide, ferric nitrate, ammonium periodate and other inorganic andorganic species. The second species may also be an acid, a base, acomplexing agent, levelers, brighteners, or any other components thatcan enhance the electroplating or the CMP processes. Note that the meretreating step without the adding step rejuvenates the chemical solution,but the adding step further rejuvenates the solution.

The present invention contains numerous advantages. First, there is atremendous cost benefit since metal and chemical solutions may bereused. The metal reclaimed in the first electroplating process may bereused in a second electroplating process and the effluent that resultedfrom the first CMP process may be reused after undergoing the treatingstep since the dissolved first species has been removed. The treatedeffluent may be combined with “fresh” slurry or be used alone. Second,since the dissolved first species is removed, and since the chemicalsolution is reused, the environmental impact of discarding the usedsolutions is lessened.

The embodiments herein have been described for use with copper, it iswell understood that the present invention may be utilized during theCMP of other materials such as tungsten, aluminum, iron, nickel,titanium, tantalum, palladium, iridium, platinum or silver. In suchcases, the consumables such as the pads, chemical solution, or abrasivesused for the process may change as is well known in the art.

What is claimed is:
 1. A method for reclaiming a metal from the effluent of a CMP process and using said reclaimed metal in an electroplating process, said method comprising the steps of: using a chemical solution in a first CMP process to remove a material from a semiconductor device, said using step producing an effluent containing a dissolved first species removed from said semiconductor device, treating said effluent by a first electroplating process to remove said dissolved first species and to produce a reclaimed metal; and using said reclaimed metal in an second electroplating process.
 2. The method of claim 1, wherein said dissolved first species is selected from the group consisting of copper, tungsten, aluminum, iron, nickel, titanium, tantalum, palladium, iridium, platinum and silver.
 3. The method of claim 1, wherein said treating step further comprises a step of adding a second species to said effluent.
 4. The method of claim 3, wherein said adding step is performed after said treating step.
 5. The method of claim 3, wherein said adding step is performed before said treating step.
 6. The method of claim 3, wherein said adding step is performed simultaneous to said treating step.
 7. The method of claim 6, wherein said adding step and said treating step are performed using an electroplating device.
 8. The method of claim 1, further comprising a step of filtering said effluent to remove a particle from said effluent.
 9. The method of claim 8, wherein said filtering step is performed after said using step and before said treating step.
 10. The method of claim 1, further comprising a step of centrifuging said effluent to remove a particle from said effluent.
 11. The method of claim 10, wherein said centrifuging step is performed after said using step and before said treating step.
 12. The method of claim 1 wherein said treating step removes said dissolved first species to produce a rejuvenated chemical solution which is used in a second CMP process.
 13. The method of claim 12, wherein said treating step further comprises a step of adding a second species to said rejuvenated chemical solution.
 14. The method of claim 13, wherein said adding step and said treating step are performed using an electroplating device.
 15. The method of claim 12, wherein said treating step further comprises a step of precipitating said dissolved first species.
 16. The method of claim 12, further comprising a step of filtering said effluent to remove a particle from said effluent.
 17. The method of claim 16, wherein said filtering step is performed after said using step and before said treating step.
 18. The method of claim 12, further comprising a step of centrifuging said effluent to remove a particle from said effluent.
 19. The method of claim 18, wherein said centrifuging step is performed after said using step and before said treating step.
 20. The method of claim 12, wherein said treating step further comprises the step of ion exchanging said effluent to remove said dissolved first species.
 21. The method of claim 12, wherein said dissolved first species is selected from the group consisting of copper, tungsten, aluminum, iron, nickel, titanium, tantalum, palladium, iridium, platinum and silver.
 22. An electroplating apparatus for reclaiming a metal from the effluent of a CMP process for use in a an electroplating process, said apparatus comprising: a CMP means for removing a material from a semiconductor device, said CMP means producing an effluent containing a dissolved first species removed from said semiconductor device a first electroplating means for treating said effluent by removing said dissolved first species to produce a reclaimed metal. a second electroplating means for using said reclaimed metal in an electroplating process.
 23. The apparatus of claim 22 wherein said CMP means and said second electroplating means are each separate chambers integrated together in one device.
 24. The apparatus of claim 22 further comprising a means for monitoring a concentration of said dissolved first species.
 25. The apparatus of claim 22 further comprising a means for monitoring a concentration of a second species.
 26. The apparatus of claim 22 wherein said treating step produces a rejuvenated chemical solution. 